If people who are ineligible to cast ballots in Colorado are on voter registration rolls, they need to be removed.

On that point, we agree with Secretary of State Scott Gessler.

However, we’re concerned that the power he is seeking from the state legislature to conduct such investigations is overly broad and undefined.

At issue is House Bill 1252, which was crafted to give Gessler authority to request proof of citizenship from any voters “who the secretary of state believes is not a citizen of the United States.”

Exactly who is of suspect status and how that determination is made is not spelled out. All the bill says is that the secretary must investigate “if evidence exists.”

Also, the measure would compel agencies to give the secretary relevant records, and while some examples are given, such as state Department of Revenue data, the information Gessler could get is not enumerated. And nothing is said about timing. If Gessler were to launch a big citizenship verification drive in the run-up to an election, we could see how it might suppress votes of some legitimate voters.

The bill would give Gessler the latitude to define much of his power through the rule-making process.

It strikes us this bill leaves too much unsaid.

In justifying his efforts to seek such power, Gessler relies on a speculative report. The analysis Gessler recently released says some 11,805 people who were non-citizens when they got driver’s licenses are currently registered to vote in Colorado.

Gessler admits he does not know how many of them have become citizens since getting driver’s licenses. But through a series of inferences, he suggests some of them are probably on the voter rolls when they shouldn’t be.

And that may be the case. We do not take issue with the broader idea that the secretary should take prudent and targeted steps to ensure the integrity of voter registration rolls.

If there is solid evidence that voters are on the rolls illegally, it must be investigated. Gessler says he needs legislative approval to send letters to the questionable registrants, asking them to produce proof of citizenship. We see no problem with that.

However, the process needs to be mindful of voter rights as enumerated in the National Voter Registration Act. A recent federal appeals court decision in Arizona is instructive on this point.

Arizona voters passed a measure in 2004 requiring those registering to vote to show proof of citizenship. The court ruled the state could not restrict voter registration in ways the federal act did not.

We are concerned that if Colorado were to engage in a widespread effort to require proof of citizenship based on scant evidence of improper registration, such an action could invite similar legal challenges.

Gessler has defined what he thinks the problem is, but now lawmakers need to spell out a more narrow and prescriptive remedy.